1. Field of the Invention
This invention generally relates to organic electronic devices and to methods for their fabrication. More particularly we will describe organic thin film transistor (TFT) structures and their fabrication.
2. Related Technology
There is a general need for improved organic electronic devices, in particular thin film transistor devices. One technique for fabricating vertical-channel polymer field-effect transistors is described in, “Self-aligned vertical-channel, polymer field-effect transistors” by N. Stutzmann, R. H. Friend, and H. Sirringhaus, Science, Vol. 299, 21 Mar. 2003, pages 1881-1884). Broadly speaking this describes a technique in which layers of the device are micro cut by a sharp wedge to provide access from the side to electrically conductive layers. This technique is useful for providing a short gate length but a device structure and fabrication method which lends itself more readily to manufacturing would be beneficial.
Parashkov et al, Appl. Phys. Lett. 82(25), 4759-4580, 2003 discloses a vertical-channel thin film transistor wherein a drain electrode is provided on a substrate; a photoresist is deposited over the drain electrode; a layer of organic conductive material PEDOT:PSS is deposited over the photoresist; the layer of PEDOT:PSS is patterned to form a source electrode; the layer of photoresist is patterned to expose the drain electrode; and the organic semiconducting material, gate dielectric and gate electrode are then deposited over the source and drain electrodes to complete the device. Again, a device structure and fabrication method which lends itself more readily to manufacturing of a vertical-channel device would be beneficial.